1. Field of the Invention
This invention relates to thin film magnetoresistive (MR) heads and more particularly to magnetoresistive (MR) head structures.
2. Description of Related Art
U.S. Pat. No. 5,639,509 of Schemmel for xe2x80x9cProcess for Forming a Flux Enhanced Magnetic Data Transducerxe2x80x9d shows a two layered bottom pole structure formed by top shield and the flux enhancement layer. The flux enhancement layer is composed of a magnetic High Moment Material (HMM) such as FeN and CoNiFe formed over a magnetic Permalloy-Like Material (PLM) top shield layer. A flux enhanced data transducer and method for producing the same in conjunction with shared shields on magnetoresistive (MR) read heads (in which substantially between 500 521 -2500 xc3x85 of a relatively higher magnetic moment material such as FeN and CoNiFe is added to the upper surface of the shared shield, or bottom write head pole, prior to a magnetic flux containment ion milling operation utilizing the upper pole as a mask) are described. The relatively higher magnetic moment flux enhancement layer may comprise CoNiFe, FeN or similar material which is deposited prior to the formation of the dielec-tric gap layer. The upper pole may be formed of NiFe deposited on a thin film seed layer of a 1 xc3x85 thick layer of a material such as NiFe or xe2x80x9cmay also comprise FeN or other relatively higher magnetic moment material such as CoNiFe.xe2x80x9d The flux enhancement layer may then be selectively removed substantially surrounding the upper pole by means of a relatively brief ion milling process in which only on the order of 1,000 xc3x85 of the layer need be removed and during which only an insignificant amount of the material removed might be re-deposited on the sides of the upper pole.
U.S. Pat. No. 5,606,478 of Chen et al. for xe2x80x9cNi45Fe55 Metal-in-Gap Thin Film Magnetic Headxe2x80x9d and U.S. Pat. No. 5,812,350 of Chen et al. for xe2x80x9cMetal-in-Gap Thin Film Magnetic Head Employing Ni45,Fe55xe2x80x9d show a pole piece P1 composed of a combination of HMM and LMM materials.
U.S. Pat. No. 5,435,053 of Krounbi et al. for xe2x80x9cSimplified Method of Making Merged MR Headxe2x80x9d shows a method for making a planarized merged pole.
With the continuous trend in the magnetic recording industry of increasing of the track density of magnetic recording, the objective of reduction of edge erasure from adjacent track writing becomes increasingly important. Edge erasure, resulting from writing fringe, can decrease the written track width and reduce drive yield by degrading off-track capacity and/or unwanted overwriting of adjacent tracks when writing. The writing fringe field often comes from a dimensional inconsistency and a mismatch of materials near the area where the flux is crowded, i.e. the gap area, of write heads. Recording on high-coercivity media especially requires the heads made of High Moment Material (HMM) for write poles and Permalloy-Like Material (PLM) for magnetoresistive (MR) shields.
Magnetic poles made of materials with a saturation magnetization higher than that of Permalloy are desirable for improving the writability of magnetic recording heads.
We have found that there is a need for a merged magnetoresistive (MR) recording heads with both High saturation Moment Material (HMM) and Permalloy. The HMM material is suitable for recording on high-coercivity media. Permalloy or Permalloy-Like Material (PLM) can function as a good sensor shield.
Edge erasure . . . Erasure by the write head that occurs outside of two edges of the the write track.
Writing fringe . . . Unintended writing along two edges of the desired write track.
Writing fringe-field . . . the magnetic field outside of the write gap causing inadvertent writing along two edges of the desired write track.
Overwrite . . . The process of writing on a disk track to erase previously written information while simultaneously writing new data.
Side writing . . . Unintended writing on two sides of a track. It may adversely affect data recorded on an adjacent track.
HMM . . . High Moment Material electroplated metals and alloys having high saturation moments or saturation magnetization (4xcfx80Ms) characteristics such as Ni45Fe55, Ni45Fe55Sn, CoNiFe, CoFeCu, Ni45Fe55Cr, and Ni45Fe55Mo.
Permalloy . . . A nickel rich alloy with iron, with a ratio just below 5:1 Ni atoms to Fe atoms, Ni79Fe9.
Permalloy Like Materialxe2x80x94PLM
PLM . . . Permalloy Like Material consists of all electroplated metals and alloys having soft-magnetic properties such as Permalloy (Ni79Fe19), NiFeCr, NiFeMo, NiFeW, NiFePd, NiFeCu, NiFeCo in which the ratio of nickel atoms to iron atoms is about 5:1 with fewer high magnetic moment iron atoms.
ABS . . . Air Bearing Surfacexe2x80x94pole tips are separated by an air gap at an ABS.
IBE . . . Ion Beam Etching
A method of manufacturing a magnetic recording head includes the following steps. Form a low magnetic moment first magnetic shield layer over a substrate.
Form a read gap layer with a magnetoresistive head over the first shield layer.
Form a seed layer over the read gap layer.
Form a frame mask with width xe2x80x9cWxe2x80x9d over the seed layer.
Form a low magnetic moment second magnetic shield layer over the read gap layer over the seed layer.
Form a non-magnetic spacer layer over the second magnetic shield layer.
Form a first high magnetic moment pole layer over the second magnetic shield layer.
Form a write gap layer over the first high magnetic moment pole layer.
Form a second high magnetic moment pole layer over the write gap layer.
Outside of the frame mask perform the step of removing the portions the second magnetic shield layer, the first high magnetic moment pole layer, the write gap layer, the second high magnetic moment pole, and the seed layer.
Preferably, employ ion beam etching to narrow the lower pole layer and the write gap layer to upper magnetic pole width xe2x80x9cNxe2x80x9d where width xe2x80x9cWxe2x80x9d is substantially greater than width xe2x80x9cNxe2x80x9d, and employ ion beam etching to pattern the first high magnetic moment pole layer to magnetic pole width xe2x80x9cNxe2x80x9d in part and flaring the remainder of the first high magnetic moment pole layer towards the width xe2x80x9cWxe2x80x9d of the second magnetic shield layer. As a result, the upper high magnetic moment pole layer has a narrow width xe2x80x9cNxe2x80x9d, the second magnetic shield layer has a width xe2x80x9cWxe2x80x9d over the second magnetic shield layer. Narrow the lower pole layer and the write gap layer to upper magnetic pole width xe2x80x9cNxe2x80x9d where width xe2x80x9cWxe2x80x9d is substantially greater than width xe2x80x9cNxe2x80x9d, and pattern the first high magnetic moment pole layer to magnetic pole width xe2x80x9cNxe2x80x9d in part and flaring the remainder of the first high magnetic moment pole layer towards the width xe2x80x9cWxe2x80x9d of the second magnetic shield layer. This structure is fashioned by using the upper pole as a mask to trim the upper high magnetic moment layer of the shared pole so that the high magnetic moment layer has the same dimension xe2x80x9cNxe2x80x9d as the top pole and its bottom part is wider with a width xe2x80x9cWxe2x80x9d.
Form a nonmagnetic spacer layer over the low magnetic moment, second magnetic shield layer, and below the lower pole layer.
The low magnetic moment second magnetic shield layer over the read gap layer is formed of a material selected from the group consisting of metals and alloys having soft-magnetic properties including Permalloy, NiFeCr, NiFeMo, NiFeW, NiFePd, NiFeCu, and NiFeCo, and the lower pole layer is formed of a material selected from the group consisting of Ni45Fe55, Ni45Fe55Sn, CoNiFe, CoFeCu, Ni45Fe55Cr, and Ni45Fe55Mo.
Sputter a PLM nickel-iron seed layer over the read gap layer prior to plating the low magnetic moment second magnetic shield layer.
Another aspect of this invention is the merged magnetic read head/write head structure produced by the above process.